Nagios Support Forum

After all this time, I just don't understand why I keep running into problems trying to set things up. You'd think by now I'd have at least a clue about what I'm doing. Well enough whining, here's what I've got.

I was trying to set up DHCP monitoring on a server on one of the other islands. No problems with the client install as the other services are reporting correctly.

So I run the DHCP Monitoring wizard, left all the fields blank, per the online video, when prompted by the wizard I enter the command:

iptables -I INPUT -I eth0 -p upd --dport 67:68 --sport

And it appears to accept that, no error, but when I force a check, I get No DHCP Offers received.

So I turn off iptables. (service iptables stop)

Same thing, no DHCP Offers received.

So I nmap the ports on the DHCP server:

nmap -p 68 -sU -PO <serveripaddress>

Says Host is up port state is open.

namp -p 67 -sU -PO <serveripaddress>

Same thing, host is up port is opened.

I get the same thing if I specify the DHCP server IP address in the Monitoring Wizard, so I'm pretty much stuck.

What am I doing wrong this time??

Mahalo

One other thing that's strange.

When I go into CCM and delete the DHCP service, that service disappears from the screen, and all other services show "Sync Missed", I've never seen that before when removing a service from within CCM.

Still nothing.

I had the local IT department create a reservation on the DHCP server for the Nagios monitoring. I specified the IP address of the DHCP server and the IP address of the reservation when I ran the monitoring wizard, still no DHCP offers.

I turned off iptables again with these new settings in the monitoring wizard, still no dhcp offers received.

This is indeed strange. You said that the port was "open", while scanning via nmap, however you didn't show us the actual output from the command.
Did you have "filtered" in the output, i.e. "open|filtered"?

[root@hhscnagios ~]# nmap -p 67 -sU -PO 10.5.110.6

Starting Nmap 5.51 ( http://nmap.org ) at 2014-08-26 10:24 HST
Nmap scan report for svrkvmh01.hhsc.org (10.5.110.6)
Host is up (0.0053s latency).
PORT STATE SERVICE
67/udp open|filtered dhcps

Nmap done: 1 IP address (1 host up) scanned in 0.32 seconds
[root@hhscnagios ~]# nmap -p 68 -sU -PO 10.5.110.6

Starting Nmap 5.51 ( http://nmap.org ) at 2014-08-26 10:24 HST
Nmap scan report for svrkvmh01.hhsc.org (10.5.110.6)
Host is up (0.0052s latency).
PORT STATE SERVICE
68/udp open|filtered dhcpc

Nmap done: 1 IP address (1 host up) scanned in 0.31 seconds

Can you run the same check_dhcp command with -v or -vvv and output the full results please?

Don't know how to do that. Here's what shows up in the Services:
Have no idea how this thing is supposed to find anything with just that in the command, but I didn't edit anything in these commands either. This is what I got from running the DHCP Monitoring Wizard

Run the following command from the CLI and show us the output:

[root@hhscnagios ~]# /usr/local/nagios/libexec/check_dhcp -vvv
DHCP socket: 3
Hardware address: 00:50:56:b4:12:e0
DHCPDISCOVER to 255.255.255.255 port 67
DHCPDISCOVER XID: 893679202 (0x35447662)
DHCDISCOVER ciaddr: 0.0.0.0
DHCDISCOVER yiaddr: 0.0.0.0
DHCDISCOVER siaddr: 0.0.0.0
DHCDISCOVER giaddr: 0.0.0.0
send_dhcp_packet result: 548




No (more) data received (nfound: 0)
Result=ERROR
Total responses seen on the wire: 0
Valid responses for this machine: 0
CRITICAL: No DHCPOFFERs were received.
[root@hhscnagios ~]#

In the Nagios XI host, the following iptables commands are required:
When you execute the check_dhcp request, the XI server must be on the same physical network segment as the DHCP server.
If you want to ensure that a specific DHCP server is working, you can target it. If you want to monitor DHCP servers at other offices, you need to execute that check over at the other office on a machine located in that office. This could be done via check_nrpe or check_by_ssh.

Does this make sense?